Colloidal carbon antihalation layer



Jan. 27, 1942. c. J. STAUD ET'AL 2,271,234

COLLQIDAL CARBON ANTIHALATION LAYER Filed June 29, 1940 -EMUL6/0/Y. yTRA/YSPAREN T J UPPOR 7:

m A/YTl-HALAT/O/YLAYER 0F [2 ALMLPSOLUBLE HATER/AL CONTAIN/N6 pups/2550 .COLLO/DAL CARBON.

GrQ/L J 57/100 M TER J WE'VERTS INVENTORS A T'TORNE Y Patented Jan. 27, 1942 i UNITED STATES PATENT OFFICE 1.com. caRBZiZZm'rIoN men J cyan I. Stand andWalter J. weyerts. Rochester,

N. Y., asalgnors to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey Application June 29,1940, Serial No. 343,254

This invention relates to photographic film and more particularly to a backing for such film for the purpose of reducing halation.

The problem of preventing halation in'photographic elements is a well known one and var-v ious means have been designedto overcome this phenomenon. Halation occurs when a light-sensitive fllm, .plate or paper is exposed to a well lighted subject and the surface of the material, opposite that first reached by the light rays, does not contain a light-absorbing material. Light rays are then reflected onto the sensitive material from the support and produce the effectknown as halation. This is ordinarily overcome by applying a light-absorbing material on one of the surfaces of the support, usually the rear surface, so that rays which would otherwise be reflected onto the sensitive layer are thereby absorbed. It is usually desirable for the light-ab sorbing material of the anti-halation layer to absorb light to which the emulsion layer'is sensitive and, inthe case ,of panchromatic or multicolor elements, the anti-halation layer should absorb light throughout the visible spectrum. It is frequently impossibieto' obtain a dye having these properties and materials such as carbon have, therefore, been proposed for use in antihalation layers. One of the disadvantages in using. carbon for'this purpose, however, is that carbon is dimcult to disperse in the anti-halation layer in suillcientlyfinely-divided form and when suitablydispersed the backing layer cannot be removed in the alkaline photographic baths.

It is, therefore,.the principal object ofthe present invention to provide an anti-halatlon layer of colloidal carbon or carbon black-which is finely dispersed in a supporting medium and which can readily be removed in alkaline photo graphic developers. A further object is to provide an anti halation layer which dissolves smoothly in photographic developers and does not disintegrate and contaminate the developer.

Other objects will appear from the following dev scription of our invention.

These objects are accomplished by using as the I anti-halation' layer an alkali-soluble material such as an alkali-soluble cellulose ester or syntheti'c resin having colloidal carbon dispersed therein with 'a water-insoluble or water-soluble dispersing agent.

' In the-accompanying'drawing the'single figure is a sectional view 'of -a photographic iilm having an anti-halation layer according to our invention.

The material which we propose touseas'anod' anti-halation backing for photographic elements comprises as a supporting material an alkali-soluble material. This material may be a cellulose ester, especially a cellulose dicarboxylic acid es- 5 ter, such as celluloseacetate phthalate or cellulose acetate proplonate maleate. Water insoluble synthetic resins may also be used, such as polyvinyl phthalate or polyvinyl acetate phthalate. In this alkali-soluble material there is dispersed carbon black or colloidal carbon in the presence of a dispersing agent which maintains the carbon in finely-divided form\in the waterinsoluble material.

Any suitable dispersing agent may be used in .15 the colloidal carbon dispersion, but-we prefer to use water-insoluble metallic soaps such as those described in ,U. S. Patents 2,173,444 and 2,173,445. Suitable water-soluble dispersing agents are Aeromls, which are sulfonated esters of dicarboxy'lic acids, and Novonacco, which is a modi-' fled sodium alkyl naphthalene sulfon'ate.

In accordance with our invention, carbon black in the form of a paste, such as that described in Sweitzer' U. S. Patent 1,987,980, granted January 2., 15, 1935, which contains as a dispersing agent a "so the form of a mixture with water containing a dispersing agent and a small amount of alkali. This mixture is run througha colloidal mill to form a smooth paste. The colloidal carbon paste obtained by either method is then mixed with an organic solvent and added to the water-insoluble celluloseester or synthetic resin dissolved in organic solvents which'is thereby used as the supporting medium. Suitable examples are as follows: 7 0 Example 1,

. The following mixtures are prepared:

. A Polyvinyl .phthalate grams 160 '4 Acetone 700 w l Methyl alcohol cc 700 Colloidal carbon paste .'.grams.- 0 Water !p I Cellosolve 700 The colloidal carbon is first thoroughly dis- .persed in the mixture of water and Cellosolve by means of a colloid mill. Solution A is then added to dispersion B and the resulting mixture run through'a colloid mill until a good dispersion of the carbon black is obtained. The final dispersion is then diluted with methyl alcohol to the desired coating consistency. If the above dispersion is mixed with about 1500 cc. of methyl alcohol a satisfactory coating dope is obtained.

Example 2 Carbon black grams l5 Emulphor O (A polyethylene-glycol condensation product).- ..grams.. 9 Polyvinyl acetate phthalate do 120 Denatured ethyl alcoholur cc 2,500

Tl'iecarbon black is mixed with a dispersing agent in 500 cc. of alcohol to form a paste. The polyvinyl acetate phthalate is dissolved in 400 cc. of alcohol and this solution is added to the paste and the mixture passed several times through a paint mill or colloid mill to prepare the final carbon dispersion. This-dispersion may be diluted for coating if desired.

Emulphor 0 is a water-soluble dispersing agent, but is also soluble in organic solvents, as

shown in Example 2. This dispersing agent can also be used to make first a dispersion of carbon black in water with the aid of a paint mill or colloid mill, and the organic solvents added later.

Our invention will now be described with particular reference to the accompanying drawing.

As shown in the drawing, a support it of any suitable material such as cellulose nitrate, cellulose acetate, cellulose -acetate propionate or synthetic resin is coated with an emulsion layer ii or with suitable subbing layers between the support iii and the emulsion layer ii, and with the anti-halation layer l2 consisting of an alkalisoluble material containing the dispersed colloidal carbon.

When film backed with a. material of the nature described above is placed in a developer or an alkaline pre-bath, the coating will be dissolved by the, alkali, releasing the carbon black which can be completely removed from the back of the film by a jet of water if it has not already been removed by the agitation of the film in the developer or pro-bath.

The layers coated according to our invention dissolve smoothly in photographic developers and do not disintegrate and come off in large pieces herein and that our invention is to be taken as limited only by the scope of the appended claims.

We claim: 1. A photographic element comprising a suptheirport having thereon a sensitive emulsion layer and an anti-halation layer of an alkali-soluble synthetic colloidal material containing colloidal carbon dispersed therein with a dispersing agent.

2. A photographic. element comprising a transparent support having on one side thereof a sensitive emulsion layer and on the opposite side an anti-halation layer of an alkali-soluble synthetic colloidal material containing colloidal carbon dispersed therein with a dispersing agent.

3. A photographic element comprising a transparent support having on one side thereof a sensitive emulsion layer and on the opposite side an antl-halation layer of an alkali-soluble cellulose ester containing colloidal carbon dispersed therein with a water insoluble dispersing agent.

4. A photographic element comprising a. transparent support having on one side thereof a sensitive emulsion layer and on the opposite side an anti-halation layer of an alkali-soluble dicarboxylic acid ester of cellulose containing colloidal carbon dispersed therein with a water-insoluble dispersing agent.

5. A photographic element comprising a transparent support having on one side thereof a sensitive emulsion layer and on the opposite side an anti-halation layer of cellulose acetate phthalate containing colloidal carbon dispersed therein with a water insoluble dispersing agent.

6. A photographic element comprising a transparent support having on one side thereof a sensitive emulsion layer and on the opposite side an anti-halation layer" of an alkali-soluble synthetic resin containing colloidal carbon dispersed therein with a water-insoluble dispersing agent.

7. A photographic element comprising a transparent support having on one side thereof a an anti-halation layer of polyvinyl acetate phthalate containing colloidal carbon dispersed therein with a dispersing agent.

9. A photographic element comprising a support having on one side thereof a panchromatic gelatino silver halide emulsion layer and on the opposite side an anti-halation layer of an alkali soluble dicarboxylic acid ester of cellulose containing carbon black dispersed therein with a water-insoluble metallic soap dispersing agent.

10. A photographic element comprising a support having on one side thereof a panchromatic gelatino-silver halide emulsion layer and on the opposite side an anti-halation layer of polyvinyl phthalate containing carbon black dispersed therein with a water-insoluble metallic soap dispersing agent.

CYRIL J. STAUD. WALTER J, WEYERTS. 

